KR20190082743A - High photoelectric conversion efficiency solar cell, manufacturing method thereof, solar cell module and solar power generation system - Google Patents

Abstract

<Task>
A back electrode type high photoelectric conversion efficiency solar cell which can be easily, inexpensively, and produced with good yields.
[Solution]
The high photoelectric conversion efficiency solar cell of the present invention is characterized in that a first conductivity type diffusion layer in which an impurity of a first conductivity type is diffused and a second conductivity type diffusion layer in which impurities of a second conductivity type are diffused A second conductivity type diffusion layer, and a high resistance layer or an intrinsic semiconductor layer formed between the first conductivity type diffusion layer and the second conductivity type diffusion layer.

Description

High photoelectric conversion efficiency solar cell, manufacturing method thereof, solar cell module and solar power generation system

The present invention relates to a back electrode type high photoelectric conversion efficiency solar cell, a manufacturing method thereof, a solar cell module, and a solar power generation system.

In general, a solar cell is a p-type semiconductor substrate made of polycrystalline silicon or monocrystalline silicon having a size of 100 to 150 mm in width and 0.1 to 0.3 mm in thickness and doped with a p-type impurity such as boron As a main material. In this solar battery cell, an n-type diffusion layer (emitter layer) and an antireflection film are formed on the light receiving surface for receiving sunlight and the antireflection film is formed so that the electrode is in contact with the emitter layer.

In the solar cell, the electrode is indispensable for drawing out the current obtained by the photoelectric conversion. However, solar light does not enter the portion where the electrode on the light receiving surface is formed due to the shielding by the electrode, The efficiency decreases and the current decreases. The loss of this current due to the electrode provided on the light receiving surface is referred to as shadow loss.

On the other hand, in the back electrode type solar cell, there is no shadow loss because there is no electrode on the light receiving surface, and almost 100% of incident solar light can be taken, except for some reflected light which can not be suppressed by the antireflection film. Therefore, high conversion efficiency can be expected in principle.

Generally, the back electrode type solar cell 100 has a sectional structure as shown in Fig. The back electrode type solar cell 100 includes a semiconductor substrate 101, an emitter layer 104, a back surface field (BSF) layer 106, antireflection film / passivation films 107 and 108, and electrodes 109 and 110 ).

The semiconductor substrate 101 is a main component of the back electrode type solar cell 100 and is made of monocrystalline silicon or polycrystalline silicon. p-type, or n-type, but an n-type silicon substrate doped with an n-type impurity such as phosphorus is often used. Hereinafter, the case where an n-type silicon substrate is used will be described as an example. The semiconductor substrate 101 is preferably a plate-like substrate having a size of 100 to 150 mm in width and 0.1 to 0.3 mm in thickness. One of the main surfaces is a light receiving surface, the other main surface is a non- .

A concave-convex structure for light confinement is formed on the light receiving surface. The concavo-convex structure is obtained by immersing the semiconductor substrate 101 in an acidic or alkaline solution for a predetermined time. In general, this concavo-convex structure is called a texture.

An emitter layer 104, which is a p-type diffusion layer doped with a p-type impurity such as boron, and a BSF layer 106, which is an n-type diffusion layer doped with an n-type impurity such as phosphorus, are formed on the back surface.

Antireflection film and passivation films 107 and 108 made of SiN (silicon nitride) are formed on the light-receiving surface on which the textured is formed and on the back surface where the emitter layer 104 and the BSF layer 106 are formed.

An electrode 109 is formed to be connected to the emitter layer 104 and an electrode 110 is formed to be connected to the BSF layer 106. These electrodes may be formed by sputtering, or the like, by using a screen printing method, in which a contact is opened by an etching paste or the like. When the screen printing method is used, a conductive silver paste containing glass frit or the like is applied to two portions of the antireflection film-passivation film 108 so as to be connected to the emitter layer 104 and the BSF layer 106 after firing And dried. The electrodes 109 connected to the emitter layer 104 and the electrodes 110 connected to the BSF layer 106 pass through the antireflection film and passivation films 107 and 108 by firing the conductive silver paste . The electrodes 109 and 110 are connected to a bus bar electrode for drawing out a photo-generated current generated in the back electrode type solar cell 100 to the outside, and a collecting finger electrode (Not shown).

In the back electrode type solar cell of the structure shown in FIG. 1, if the length of the adjacent pair of the emitter layer, which is a p-type diffusion layer and the BSF layer, is long in the back side, Leakage current easily flows through the tunnel effect or through the impurity level, and it is difficult to increase the conversion efficiency.

When the emitter layer and the BSF layer are adjacent to each other, when the electrodes are formed on one of the layers, the formation position is shifted and the electrodes are also connected to the other layer, which may lower the parallel resistance. The occurrence of this problem is particularly remarkable when the electrodes are formed on the BSF layer, which is generally formed to have a narrow width as compared with the emitter layer.

These problems can be avoided by forming the emitter layer and the BSF layer at a predetermined interval in the back surface. At this time, it is preferable that the interval between the emitter layer and the BSF layer is suitably narrow. However, if it is attempted to control the interval to an order of several mu m to several tens of mu m, the manufacturing cost is high and the productivity is also lowered. On the other hand, if the interval is widened to the order of several hundreds of micrometers, the area of the emitter layer must be made relatively small, whereby the collection efficiency of the minority carriers decreases and the current decreases. That is, the conversion efficiency deteriorates.

Thus, a method of spatially separating both layers by punching a trench between the emitter layer and the BSF layer with a laser or the like has been proposed (see Patent Document 1 and Non-Patent Document 1). However, in addition to the risk of damaging the semiconductor substrate main body and deteriorating the conversion efficiency, this processing increases the manufacturing cost by the addition of the machining process. In addition, when the separation of both layers is incomplete and a portion not separated is left, when a reverse voltage is applied to the solar cell, the leakage current is concentrated at the portion where the separation is not performed. For example, when a part of the module is shaded when the solar cell is modularized, a reverse voltage is applied to the solar cell in the shaded location, and the leakage current is concentrated. In this way, there is a risk of ignition because the temperature is locally high at the portion where the leakage current is concentrated.

In order to eliminate this risk, the maker of the solar cell or the module assembles the bypass diode into the module and measures the leakage current of the cell when the reverse voltage is applied, We take action that we do not ship as product. However, in the back electrode type solar cell, since the boundary between the emitter layer, which is a p-type diffusion layer, and the BSF layer, which is an n-type diffusion layer, is very long as compared with a general solar cell, it is difficult to satisfy the standard value. Therefore, when the standard value is strictly applied in consideration of performance or safety, the yield is deteriorated, and when the yield is emphasized, the performance or safety is lowered.

Japanese Patent Publication No. 2013-521645

 Ngwe Zin et al., "LASER-ASSISTED SHUNT REMOVAL ON HIGH-EFFICIENCY SILICON SOLAR CELLS," 27th European Photovoltaic Solar Energy Conference and Exhibition

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a back electrode type high photoelectric conversion efficiency solar cell which can be easily produced at low cost and in good yield, a method for producing the same, a solar cell module, The purpose is to provide.

(1) A high photoelectric conversion efficiency solar cell of the present invention is characterized in that a first conductive type diffusion layer in which impurities of a first conductive type are diffused and a second conductive type diffusion layer in which a second conductive type impurity And a high resistance layer or an intrinsic semiconductor layer formed between the first conductivity type diffusion layer and the second conductivity type diffusion layer. (2) At this time, either one of the first electrode connected to the first conductivity type diffusion layer and the second electrode connected to the second conductivity type diffusion layer may be connected to the high resistance layer or the intrinsic semiconductor layer.

Since the first conductivity type diffusion layer and the second conductivity type diffusion layer, which correspond to the BSF layer and the emitter layer, are simply separated by the high resistance layer or the intrinsic semiconductor layer as described above, they can be easily manufactured at low cost, I can do it. By separating the emitter layer and the BSF layer by the high-resistance layer or the intrinsic semiconductor layer, when a voltage is applied in the operating state, that is, in the forward direction, the leakage current is cut off and the parallel resistance is not lowered. A solar cell of a good back electrode type is obtained. When a voltage is applied in the reverse direction, current is uniformly leaked in the cell surface, so that it is not locally hot, and fatal damage such as ignition does not occur, thereby improving reliability. In addition, when electrodes are formed in the emitter layer or the BSF layer, even if the positions are shifted, they are only connected to the high-resistance layer or the intrinsic semiconductor layer, so that the lowering of the parallel resistance can be prevented.

(3) When a step is formed on the back surface of the semiconductor substrate and one of the first conductivity type diffusion layer and the second conductivity type diffusion layer is formed on the upper end and the other is formed on the lower end, A semiconductor layer may be formed on the upper surface. As a result, when the electrode is formed, it is difficult to connect the upper end to the upper end, particularly when the electrode is formed in the conductive diffusion layer on one of the lower conductive diffusion layers by fire through, Or the intrinsic semiconductor layer is formed, it becomes difficult to connect to the other conductive diffusion layer.

(4) When viewed from above, the high-resistance layer or the intrinsic semiconductor layer may be formed to have a width that separates the first conductivity type diffusion layer and the second conductivity type diffusion layer at intervals of 1 占 퐉 or more and 100 占 퐉 or less . As a result, the effect of improving the conversion efficiency due to the interruption of the leakage current can be more reliably obtained.

(5) The high-resistance layer can be easily formed by, for example, diffusing both the impurity of the first conductivity type and the impurity of the second conductivity type.

(6) A method of manufacturing a high photoelectric conversion efficiency solar cell according to the present invention is a method for manufacturing a high photoelectric conversion efficiency solar cell, comprising the steps of: forming, on a back surface of a first conductive semiconductor substrate having a third region from a first region, Forming a second conductive type diffusion layer in which impurities are diffused, forming a first conductive type diffusion layer in which impurities of the first conductive type are diffused in the second region, and forming a second conductive type diffusion layer in the third region between the first and second regions, 1. A method for manufacturing a high photoelectric conversion efficiency solar cell in which a high-resistance layer in which impurity of one conductivity type and impurity of the second conductivity type are diffused is provided, comprising the steps of: Forming a protective film on the second conductive type diffused layer; forming a protective film on a portion of the protective film covering the third region from a boundary of a portion covering the first region to a thickness of the first conductive type diffused layer; Toward the boundary of the portion covering the second region, And a second protective film removing step of removing the second conductive type diffusion layer from which the protective film is removed to expose the second region so as to expose the second region, A second conductive type diffusion layer removing step and a second conductive type diffusion layer removing step of diffusing the impurity of the first conductivity type in the third region through the continuously thinned portion of the second region and the protective film, 1 impurity diffusion step, and a second protective film removing step for removing the remaining protective film.

(7) Another method for manufacturing a high photoelectric conversion efficiency solar cell according to the present invention is a method for manufacturing a high-photoelectric conversion-efficiency solar cell comprising the steps of: forming a first conductive semiconductor substrate having a third region from a first region, Forming a second conductivity type diffusion layer in which impurities of the first conductivity type are diffused in the first region and a first conductivity type diffusion layer in which impurities of the first conductivity type are diffused in the second region; A method for manufacturing a high photoelectric conversion efficiency solar cell in which a high-resistance layer in which an impurity of a first conductivity type and an impurity of a second conductivity type are diffused is provided. The impurity of the first conductivity type is diffused over the entire back surface of the semiconductor substrate, The method comprising the steps of: forming a first impurity diffusion step for forming a first conductivity type diffusion layer on the first conductivity type diffusion layer; forming a protective film on the first conductivity type diffusion layer; Toward the boundary of the portion covering the second region, A first protective film removing step of removing the portion covering the second region of the protective film, and a second protective film removing step of removing the exposed portion of the first conductive type diffusion layer to expose the second region, The first conductive type diffusion layer removing step and the second conductive type diffusion layer and the high resistance layer are formed by diffusing the impurity of the second conductivity type in the third region through the continuously thinned portion of the second region and the protective film A second impurity diffusion step, and a second protective film removing step for removing the remaining protective film.

By separating the second conductivity type diffusion layer, which is an emitter layer, and the first conductivity type diffusion layer, which is a BSF layer, into a high-resistance layer or an intrinsic semiconductor layer which can be formed easily and with high yield, That is, when a voltage is applied in the forward direction, the leakage current is cut off and the parallel resistance is not lowered, so that a solar cell having a high conversion efficiency can be obtained. Further, when a voltage is applied in the reverse direction, the current leaks uniformly in the cell surface, so that it is not locally hot, and fatal damage such as ignition does not occur. In addition, when electrodes are formed in the emitter layer or the BSF layer, even if the positions are shifted, they are only connected to the high-resistance layer or the intrinsic semiconductor layer, so that the lowering of the parallel resistance can be prevented.

(8) The removal and the thinning of the protective film in the first protective film removing step can be performed, for example, by applying an etching paste to a portion covering the second region of the protective film or by irradiating a laser. The application of the etching paste to the portion covering the second region or the irradiation of the laser is carried out so that the energy of the etchant or the laser flowing out of the etching paste propagates to the portion covering the third region adjacent to the second region , The energy reaching from the farthest front position over the boundary between the third region and the second region is continuously increased. Therefore, not only the protective film of the second region can be removed, but also the protective film of the third region can be partially removed so as to be continuously thinned from the film thickness to substantially zero.

(9) The protective film may be a silicon oxide film, a silicon nitride film, a glass layer containing an impurity, or a laminate obtained by laminating two or more thereof. Therefore, for example, by using the glass layer formed at the time of impurity diffusion as it is as a protective film, it is possible to omit the step of removing the glass layer, thereby making it easier and economical to manufacture.

(10) A solar cell module may be constructed by connecting a plurality of high photoelectric conversion efficiency solar cells of the present invention.

(11) A photovoltaic power generation system may be constructed using a solar cell module constituted by connecting a plurality of solar cells of the present invention.

1 is a view showing an example of the configuration of a conventional back electrode type solar cell.
2 is a view showing a configuration of a back electrode type solar cell of the present invention.
3 is a flowchart showing a manufacturing method of the back electrode type solar cell of the present invention.
4 is another diagram showing the configuration of the back electrode type solar cell of the present invention.
5 is a flow chart showing another method of manufacturing the back electrode type solar cell of the present invention.
6 is a schematic view showing a configuration example of a solar cell module configured using the back electrode type solar cell of the present invention.
7 is a schematic view showing a configuration example of the back surface of the solar cell module shown in Fig.
8 is a schematic view showing a structural example of a cross section of the solar cell module shown in Fig.
Fig. 9 is a schematic diagram showing a configuration example of a solar power generation system configured using the solar cell module shown in Fig. 6. Fig.

Hereinafter, embodiments of the present invention will be described. Common elements in the drawings are denoted by the same reference numerals as those used in the description of the background art.

[First Embodiment]

Fig. 2 (a) shows the structure of the back electrode type solar cell 200 according to the present invention. The back electrode type solar cell 200 includes a semiconductor substrate 101, an emitter layer 104, a BSF layer 106, antireflection films / passivation films 107 and 108, electrodes 109 and 110, (202). The back electrode type solar cell 200 is formed by forming the high resistance layer 202 between the emitter layer 104 and the BSF layer 106 of the conventional back electrode type solar cell 100 shown in FIG. Hereinafter, a manufacturing process of the back electrode type solar cell 200 will be described with reference to FIG.

The semiconductor substrate 101 is the main material of the back electrode type solar cell 200 and is made of single crystal silicon or polycrystalline silicon. The case of an n-type silicon substrate containing impurities such as phosphorus and having a specific resistance of 0.1 to 4.0? · cm will be described by way of example. The semiconductor substrate 101 is preferably of a plate shape having a size of 100 to 150 mm in width and 0.05 to 0.30 mm in thickness, and one of the main surfaces is used as a light receiving surface and the other main surface is used as a non-light receiving surface (back surface) .

Prior to the fabrication of the back electrode type solar cell 200, the semiconductor substrate 101 is dipped in an acidic solution or the like to damage etch the surface to remove damages on the surface by slicing, etc., and clean and dry.

An emitter layer 104 is formed on the back surface of the semiconductor substrate 101 after damaged etching (S1). First, a protective film 102 such as a silicon oxide film is formed on the entire surface of the semiconductor substrate 101 (S1-1). Specifically, for example, a silicon oxide film having a film thickness of about 30 to 300 nm is formed by thermal oxidation in which a semiconductor substrate 101 is provided at a high temperature of 800 to 1100 DEG C in an oxygen atmosphere. Next, a resist paste is applied by screen printing to a portion of the protective film 102 covering the region other than the region where the emitter layer 104 is to be formed on the back surface of the semiconductor substrate 101 (S1-2 ). Subsequently, the protective film 102 covering the region where the emitter layer 104 is to be formed is dipped in an aqueous solution of hydrofluoric acid to remove the resist paste 103 (S1-4). Next, the p-type impurity element is diffused by, for example, thermal diffusion method to the region from which the protective film 102 is removed to form the emitter layer 104 and the glass layer 105 which are p-type diffusion layers (S1-5) . Concretely, for example, boron is diffused into a portion where the protective film 102 is not formed by providing this semiconductor substrate 101 in a high-temperature gas containing BBr ₃ at 800 to 1100 ° C, The emitter layer 104 and the glass layer 105 of about 300? /? Are formed. Subsequently, the remaining protective film 102 and the glass layer 105 are removed by immersing in a chemical agent such as a diluted hydrofluoric acid solution, and then cleaned with pure water (S1-6). Thereby, the emitter layer 104 in which the p-type impurity is diffused is formed at a desired location on the back surface of the semiconductor substrate 101.

Next, a BSF layer 106 and a high-resistance layer 202 are formed on the back surface of the semiconductor substrate 101 as follows (S2).

A protective film 102 such as a silicon oxide film is formed on the entire surface of the semiconductor substrate 101 on which the emitter layer 104 is formed (S2-1). Specifically, for example, a silicon oxide film having a film thickness of about 30 to 300 nm is formed by thermal oxidation in which a semiconductor substrate 101 is provided at a high temperature of 800 to 1100 DEG C in an oxygen atmosphere.

An etching paste 201 for etching the protective film 102 is applied by screen printing to a portion of the protective film 102 protecting the region where the emitter layer 104 is not formed on the back surface of the semiconductor substrate 101, And dried (S2-2).

At this time, the etching solution seeps from the printing portion immediately after the printing to the heating. Therefore, if the etching paste 201 is removed by immersing the semiconductor substrate 101 coated with the etching paste 201 in an aqueous solution of potassium hydroxide or the like to remove portions of the protective film 102 printed with the etching paste 201 Not only the thickness becomes almost zero but also the protective film 102 on the emitter layer 104 adjacent to the portion where the etching paste 201 is printed is continuously thinned from the film thickness (S2-3). That is, since the amount of the etching solution gradually increases from the position farthest from the emitter layer 104 on which the etching liquid permeated from the printing position reaches, to the position where the etching paste 201 is applied, the thickness of the protective film 102 It is possible to form a continuously thinned portion until the film thickness becomes almost zero from the film thickness.

Next, the n-type impurity element is diffused by a thermal diffusion method, for example, to a portion where the thickness of the protective film 102 is substantially zero and a portion which is continuously thinned by removing the etching paste 201. Specifically, for example, the semiconductor substrate 101 is placed in a high-temperature gas containing POCl _{3 at} 850 to 1100 ° C. As a result, the BSF layer 106 and the glass layer 105, which are n-type diffusion layers having a sheet resistance of about 30 to 300? / ?, are formed at portions where the thickness of the protective film 102 is almost zero. At the same time, the portions where the thickness of the protective film 102 is continuously thinned include a portion where boron diffused for forming the emitter layer 104 and phosphorus diffused through the thinned protective film 102 are mixed with each other, (Step S2-4). It is presumed that the sheet resistance of the thus-formed high-resistance layer 202 is difficult to accurately measure, and depends on the mixed state of the impurities, but is estimated to be several hundreds to several thousands ohms / square or more.

The width of the high resistance layer 202 formed between the emitter layer 104 and the BSF layer 106 can be controlled by adjusting the amount of seepage by changing the viscosity of the etching paste 201. The width of the high resistance layer 202 is required to prevent leakage current from flowing between the emitter layer 104 and the BSF layer 106 and from the viewpoint of absorbing the deviation of the electrode formation position, And 100 mu m or less from the viewpoint of ensuring the minimum necessary area required for the emitter layer 104. [

Subsequently, the remaining protective film 102 and the glass layer 105 are removed by immersing in, for example, diluted hydrofluoric acid solution or the like, and cleaned with pure water (S2-5). The BSF layer 106 in which the n-type impurity is diffused is formed in the region where the emitter layer 104 is not formed on the back surface of the semiconductor substrate 101 and the emitter layer 104 and the BSF layer 106 are formed, A high resistance layer 202 in which both the n-type impurity and the p-type impurity are diffused is formed.

Next, a concavo-convex structure called a texture is formed on the light receiving surface of the semiconductor substrate 101 (S3). The texture can be formed by immersing the semiconductor substrate 101 in an acidic or alkaline solution for a certain period of time. For example, a resist paste is coated on the entire back surface of the semiconductor substrate 101 by screen printing and cured, followed by chemical etching with an aqueous potassium hydroxide solution, followed by cleaning and drying. Since the light incident from the light receiving surface is reflected and confined in the semiconductor substrate 101 by forming the texture, the reflectance is effectively reduced and the conversion efficiency can be improved. Thereafter, the resist paste applied on the whole back surface of the semiconductor substrate 101 is removed by immersing it in acetone or the like. Further, the texture may be performed before forming the emitter layer 104 and the BSF layer 106. A texture may also be formed on the back surface of the semiconductor substrate 101. Further, an FSF (Front Surface Field) layer may be further formed on the light receiving surface of the semiconductor substrate 101.

Subsequently, antireflection film-passivation films 107 and 108 made of SiN (silicon nitride) are formed on both surfaces of the semiconductor substrate 101 (S4). In the case of the silicon nitride film, for example, a plasma CVD method is used in which a mixed gas of SiH ₄ and NH ₃ is diluted with N ₂ , and is deposited by glow discharge decomposition into plasma. The refractive index is formed to be about 1.8 to 2.3 and the thickness to be about 50 to 100 nm in consideration of the refractive index difference with the semiconductor substrate 101 and the like. This film prevents the light from reflecting on the surface of the semiconductor substrate 101 and functions to effectively take the light in the semiconductor substrate 101. In addition, the film serves as a passivation film having a passivation effect for the n-type diffusion layer So as to improve the electrical characteristics of the solar cell. The antireflection film and passivation films 107 and 108 may be a single layer film of silicon oxide, silicon carbide, amorphous silicon, aluminum oxide, or titanium oxide, or a laminated film obtained by combining these films. It is also possible to use another film on the light receiving surface and the back surface of the semiconductor substrate 101. [

Subsequently, electrodes 109 and 110 are formed (S5). The electrode may be formed by sputtering, for example, by providing an opening in the antireflection film-passivation film 108 with an etching paste or the like, or may be formed by a screen printing method. The surface of the antireflection film and passivation film 108 which forms the electrode 109 connected to the emitter layer 104 and the electrode 110 connected to the BSF layer 106 A conductive paste containing, for example, silver powder, glass frit, varnish, and the like is screen printed and dried on each of the forming portions. Then, the printed conductive paste is fired at a temperature of about 500 캜 to 950 캜 for about 1 to 60 seconds to pass through the antireflection film-passivation film 108 (fire through). As a result, the sintered silver powder is conducted to the emitter layer 104 or the BSF layer 106 to form the electrodes 109 and 110. The firing at the time of electrode formation may be performed once or divided into a plurality of circuits. The conductive paste to be applied on the emitter layer 104 and the conductive paste to be applied on the BSF layer 106 may be different.

Each electrode is composed of a bus bar electrode for drawing out a photo-generated current generated in the solar battery cell to the outside, and a collecting finger electrode connected to the bus bar electrode.

As can be understood from the above description, the high-resistance layer 202 can be easily formed at a low cost and a high yield. Thus, by separating the emitter layer 104 from the BSF layer 106, leakage current is blocked when a voltage is applied in the operating state, that is, in the forward direction, so that the parallel resistance is not lowered. A solar cell is obtained. Further, when a voltage is applied in the reverse direction, the current leaks uniformly in the cell surface, so that it is not locally hot, and fatal damage such as ignition does not occur.

The presence of the high-resistance layer 202 allows the electrodes 109 and 110 to be formed on either one of the emitter layer 104 and the BSF layer 106, it is possible to prevent the parallel resistance caused by the electrodes 109 and 110 being connected to the other layers from being lowered since the electrodes 109 and 110 are connected to the high resistance layer 202 as shown in FIG.

As described above, according to the structure and the manufacturing method of the back electrode type solar cell of the present invention, it is possible to produce a back electrode type solar cell having a conventional structure easily, inexpensively, at a low yield, A back electrode type solar cell can be provided.

The portion where the thickness of the protective film is continuously thinned can be formed by a method of irradiating laser instead of the method of applying the etching paste. That is, in the above embodiment, by irradiating a laser to the portion of the protective film 102 covering the region where the BSF layer 106 of the semiconductor substrate 101 is to be formed, energy is injected into the protective film 102 of the portion, , The energy also propagates to the portion of the protective film 102 covering the emitter layer 104 adjacent to the irradiated portion of the laser. Since the overall intensity of the energy is continuously increased over the portion irradiated from the farthest reaching position of the irradiated energy, a portion where the thickness of the protective film 102 is continuously thinned can be formed. A portion of the protective film 102 covering the region where the high resistance layer 202 is to be formed is covered with a strong fluorescence laser in the portion of the protective film 102 covering the region where the BSF layer 106 is formed, By irradiating each of the fluens, it is possible to control the film thickness more precisely.

By employing the method of removing the protective film by laser irradiation, the step of printing, heating, and drying the complicated and expensive etching paste can be omitted. That is, in the manufacturing process of Fig. 3, the two steps S2-2 and S2-3 can be performed in one step of irradiating the laser. Therefore, the manufacturing cost can be further reduced.

[Second embodiment]

In the manufacturing method of the first embodiment, the BSF layer is formed in a region where the emitter layer on the back surface is not formed after the emitter layer is formed on a part of the back surface of the semiconductor substrate. However, After forming the BSF layer, the BSF layer may be formed by removing the emitter layer where the BSF layer is to be formed by alkali etching or the like. The configuration of the back electrode type solar cell 200 manufactured by the manufacturing method of the second embodiment is shown in Fig. 4 (a), and the manufacturing process is shown in Fig.

The semiconductor substrate 101 may be either n-type or p-type, as in the first embodiment. Here, the case of an n-type silicon substrate will be described by way of example. First, the emitter layer 104 is formed on the entire back surface as follows (S6). The protective film 102 is formed on the entire surface of the semiconductor substrate 101 after damage etching (S6-1), and the protective film over the entire back surface is removed (S6-2). Next, the p-type impurity is diffused over the entire back surface to form the emitter layer 104 and the glass layer 105 which are p-type diffusion layers (S6-3), and the protective film 102 and the glass layer 105 are removed S6-4). As a result, the emitter layer 104 can be formed on the entire back surface of the semiconductor substrate 101.

Next, the BSF layer 106 and the high-resistance layer 202 are formed on the back surface of the semiconductor substrate 101 as follows (S7). First, the protective film 102 is formed on both sides of the semiconductor substrate 101 on which the emitter layer 104 is formed on the entire back surface (S7-1).

Then, the etching paste 201 is applied by screen printing to the portion of the protective film 102 covering the region where the BSF layer 106 is to be formed, heated and dried (S7-2). At this time, the etching solution seeps from the printing portion immediately after the printing to the heating.

Therefore, if the etching paste 201 is removed by immersing the semiconductor substrate 101 coated with the etching paste 201 in an aqueous solution of potassium hydroxide or the like to remove portions of the protective film 102 printed with the etching paste 201 Not only the thickness becomes almost zero but also the protective film 102 on the emitter layer 104 adjacent to the portion where the etching paste 201 is printed is continuously thinned from the film thickness (S7-3). That is, since the amount of the etching solution gradually increases from the position farthest from the emitter layer 104 on which the etching liquid permeated from the printing position reaches, to the position where the etching paste 201 is applied, the thickness of the protective film 102 It is possible to form a continuously thinned portion until the film thickness becomes almost zero from the film thickness.

Subsequently, the emitter layer 104 formed in the region for forming the BSF layer 106 of the semiconductor substrate 101 is removed by alkali etching or the like (S7-4). Then, the n-type impurity is diffused by a thermal diffusion method, for example, in a region where the emitter layer 104 of the semiconductor substrate 101 is removed and a portion where the protective film 102 is continuously thinned. As a result, the BSF layer 106 and the glass layer 105, which are n-type diffusion layers, are formed in the region where the emitter layer 104 is removed. At the same time, the portion where the protective film 102 is continuously thinned includes a high-resistance layer 202 in which boron diffused in advance for forming the emitter layer 104 and phosphorus diffused through the thinned protective film 102 are mixed with each other, (S7-5). Then, the remaining protective film 102 and the glass layer 105 are removed (S7-6). The BSF layer 106 in which the n-type impurity is diffused is formed in the region where the emitter layer 104 is not formed on the back surface of the semiconductor substrate 101 and the emitter layer 104 and the BSF layer 106 are formed, Resistance layer 202 in which both the n-type impurity and the p-type impurity are diffused is formed.

According to the method of the second embodiment, since the step of patterning the resist for partially forming the emitter layer becomes unnecessary, the process can be reduced as compared with the method of the first embodiment, and the manufacturing cost can be further reduced have.

In this method, the emitter layer is once formed on the entire surface of the semiconductor substrate, and then the emitter layer of the portion forming the BSF layer is removed. Therefore, as shown in FIG. 4A, (I.e., a region where the emitter layer and the high-resistance layer are formed) and a region where the emitter layer and the high-resistance layer are not removed. Specifically, when viewed from above, the emitter layer and the high-resistance layer are formed at the upper end, and the BSF layer is formed at the lower end adjacent to the high-resistance layer. By forming such a step, it is difficult to connect to the upper end when the electrode is formed, particularly, when the electrode is formed by the through-hole in the lower BSF layer. Therefore, (See Fig. 4 (b)). In this case, the emitter layer is more likely to be connected to the emitter layer.

Although the emitter layer is formed on the entire back surface of the semiconductor substrate, the emitter layer where the BSF layer is to be formed is removed, and the BSF layer is formed at the removed portion. However, The BSF layer where the emitter layer is to be formed may be removed and then the emitter layer may be formed at the removed position. In this case, when viewed from above, the BSF layer and the high-resistance layer are formed on the upper side, and the emitter layer is formed on the lower side adjacent to the high-resistance layer.

[Modifications]

In each of the above embodiments, the semiconductor substrate is an n-type silicon substrate. In the case of a p-type silicon substrate, the emitter layer may be an n-type diffusion layer and the BSF layer may be a p-type diffusion layer.

In each of the above-described embodiments, the case where the high-resistance layer is formed between the emitter layer and the BSF layer is exemplified, but an intrinsic semiconductor layer may be provided instead of the high-resistance layer. Since the intrinsic semiconductor has a very low carrier density, it is possible to prevent a leakage current from flowing between the emitter layer and the BSF layer, similarly to the case where the high-resistance layer is provided. In addition, the presence of the intrinsic semiconductor layer causes the electrode to be connected to the other layer only when the electrodes are formed on either one of the emitter layer and the BSF layer, It is possible to prevent the parallel resistance from being lowered.

In each of the above embodiments, the case where the protective film is a silicon oxide film is exemplified. However, it is not necessarily a silicon oxide film. For example, a silicon nitride film, a glass layer containing impurities formed at the time of pre- Chere is also good. In the case where the protective film is a silicon nitride film, for example, when formed by the plasma CVD method, since it is not necessary to apply a high temperature, contamination of a lifetime killer caused by high temperature can be prevented. If the glass layer formed at the time of diffusion of impurities is directly used as a protective film, the step of forming a protective film can be reduced, and the manufacturing cost can be further reduced.

The back electrode type solar cell fabricated according to each of the above embodiments can be used in a solar cell module. 6 is a schematic view showing a configuration example of the solar cell module 300. As shown in Fig. The solar cell module 300 has a plurality of back electrode type solar cell units 200 laid out in a tile shape. A plurality of back-surface electrode type solar cells 200 constitute a series circuit in which several to several tens of sheets adjacent to each other are electrically connected in series to form a string. An overview of the string is shown in Fig. 7 corresponds to a schematic view of the inner back side of the solar cell module 300 which is normally invisible to a person. In Fig. 7, illustration of a finger or a bus bar is omitted for clarity of description. In order to constitute a series circuit, the P bus and N bus bars of the back electrode type solar cell 200 adjacent to each other are connected by a lead wire 320. 8 is a schematic cross-sectional view of the solar cell module 300. As shown in FIG. As described above, the string is constituted by connecting a plurality of back electrode type solar cell 200 and a lead wire 320 to the bus bar 310. The string is usually encapsulated with a translucent filler 330 such as EVA (ethylene vinyl acetate), the weatherproof side (back side) side is coated with a weather resistant resin film 340 such as PET (polyethylene terephthalate), and a light receiving side is soda lime glass -lime glass or the like and has a high mechanical strength. As the filler 330, polyolefin, silicone, etc. may be used in addition to EVA.

In addition, a plurality of solar modules may be connected to constitute a solar power generation system. 9 is a schematic diagram showing a configuration example of a solar power generation system 400 in which a plurality of solar cell modules 300 configured by a plurality of back electrode type solar cell 200 of the present invention are connected. The solar power generation system 400 includes a plurality of solar cell modules 300 connected in series by wiring 410 and supplies generated power to an external load circuit 430 via an inverter 420. Although not shown in Fig. 9, the photovoltaic generation system may further include a secondary battery for storing the generated electric power.

In addition, the present invention is not limited to the above-described embodiments and modifications. It is to be understood that the embodiments are illustrative and substantially the same as the technical ideas described in the claims of the present invention are included in the technical scope of the present invention.

Example

The effects of the present invention were evaluated by the products manufactured by the methods shown in the following Comparative Examples and Examples.

An n-type silicon substrate made of n-type single crystal silicon having a resistivity of about 1? 占 제작 m prepared by slicing a silicon substrate with a thickness of 0.2 mm was prepared and subjected to an outer diameter machining process to form a square 15 cm square. Then, this substrate was immersed in a boric acid solution for 15 seconds to damage and etch, then cleaned with pure water and dried.

&Lt; Comparative Example 1 &

In Comparative Example 1, a back electrode type solar cell was manufactured by a conventional method. Specifically, the following steps were carried out and then the first and second common processes described later were carried out.

The n-type silicon substrate after damage etching was thermally oxidized in an oxygen atmosphere at a temperature of 1000 캜 for 120 minutes to form a silicon oxide film with a thickness of 70 nm on both sides of the substrate. Then, a resist paste of the silicon oxide film formed on the back surface of the substrate was screen-printed on the BSF layer formation site and dried at a temperature of 100 캜. Here, the screen printing plate was formed in a pattern such that the emitter layer had a width of 800 mu m and the BSF layer had a width of 200 mu m, such that the emitter layer and the BSF layer were alternately formed in the interdigitated back contact cell structure. As the resist paste, 185 paste manufactured by LEKTRACHEM was used. The substrate was immersed in a 2% hydrofluoric acid aqueous solution to partially remove the silicon oxide film while leaving the BSF layer formation site, and then immersed in acetone to remove the resist paste, followed by washing with pure water and drying. Next, to form a, BBr ₃ gas in the atmosphere, and by carrying out a thermal diffusion treatment under the conditions of 20 minutes at a temperature of 900 ℃, the diffused p-type emitter layer on the back surface of the substrate and the glass layer on the rear surface of the substrate. The sheet resistance of the formed p-type diffusion layer was about 70? / ?, and the diffusion depth was 0.5 占 퐉. Thereafter, this substrate was immersed in a 25% aqueous solution of hydrofluoric acid, washed with pure water and dried to remove the silicon oxide film and the glass layer.

The substrate on which the emitter layer was formed as described above was thermally oxidized in an oxygen atmosphere at a temperature of 1000 DEG C for 120 minutes to form a silicon oxide film with a thickness of 70 nm on both sides of the substrate. Then, a resist paste of the silicon oxide film formed on the back surface of the substrate was screen-printed on the portion where the emitter layer was formed, heated at a temperature of 100 캜 and dried. As the resist paste, a 185 paste manufactured by LEKTRACHEM was used. The substrate was immersed in a 2% aqueous solution of hydrofluoric acid to partially remove the silicon oxide film while leaving a portion on which the emitter layer was formed, and then immersed in acetone to remove the resist paste.

&Lt; Example 1 &gt;

In Example 1, a back electrode type solar cell was manufactured by the method of the first embodiment. Specifically, the following steps were carried out and then the first and second common processes described later were carried out.

The substrate on which the emitter layer was formed as in Comparative Example 1 was thermally oxidized in an oxygen atmosphere at a temperature of 1000 占 폚 for 120 minutes to form a silicon oxide film with a thickness of 70 nm on both sides of the substrate. Then, an etching paste was screen-printed on the silicon oxide film formed on the back surface of the substrate on the BSF layer formation site where the emitter layer was not formed, heated at 300 캜 and dried. Here, SolarEtch (registered trademark) BES Type 10 paste manufactured by Merck was used as the etching paste. Then, the substrate was immersed in a solution containing 1% of potassium hydroxide to remove the etching paste. According to this method, the silicon oxide film was removed immediately after the etching paste was printed, that is, the portion where the BSF layer where no emitter layer was to be formed was formed, and the film thickness became almost 0 nm. Further, the thickness of the silicon oxide film on the emitter layer continuously thinned from 70 nm to 0 nm at both ends of 30 mu m from the printed portion by the etching liquid permeated from the printed etching paste.

&Lt; Example 2 &gt;

In Example 2, a back electrode type solar cell was manufactured by the method of the second embodiment. Specifically, the following steps were carried out and then the first and second common processes described later were carried out.

The entire back surface of the n-type silicon substrate after the etching damage, in the BBr ₃ gas atmosphere, and by carrying out a thermal diffusion treatment under the conditions of 20 minutes at a temperature of 900 ℃, has already formed the emitter layer of p-type diffusion layer and the glass layer. The sheet resistance of the formed p-type diffusion layer was about 70? / ?, and the diffusion depth was 0.5 占 퐉. This substrate was immersed in a 25% aqueous solution of hydrofluoric acid, then rinsed with pure water and dried to remove the glass layer. The substrate on which the glass layer was removed was thermally oxidized in an oxygen atmosphere at a temperature of 1000 DEG C for 120 minutes to form a silicon oxide film with a thickness of 70 nm on both sides of the substrate. Then, an etching paste was screen-printed on a portion of the silicon oxide film formed on the back surface of the substrate where a BSF layer is to be formed, and heated at 300 캜 for drying. Here, SolarEtch (registered trademark) BES Type 10 paste manufactured by Merck was used as the etching paste. Then, the substrate was immersed in a solution containing 1% of potassium hydroxide to remove the etching paste. This substrate was immersed in a solution at 70 캜 containing 25% potassium hydroxide for 5 minutes to remove the p-type diffusion layer remaining in the place where the BSF layer was to be formed, by chemical etching, and then washed with pure water and dried. According to this method, the portion where the etching paste was printed, that is, the portion for forming the BSF layer, the thickness of the silicon oxide film was 0 nm, and the level was lower than the portion where the emitter layer was formed, and a step was formed. In addition, the thickness of the silicon oxide film on the emitter layer continuously thinned from 70 nm to 0 nm over both sides of 30 mu m from the etching paste printing portion by the etching liquid permeated from the etching paste after printing.

&Lt; Example 3 &gt;

In the third embodiment, in the step of removing the protective film of the second embodiment, a back electrode type solar cell was manufactured by employing a method of irradiating a laser in place of the method of applying an etching paste. Specifically, the following steps were carried out and then the first and second common processes described later were carried out.

The entire back surface of the n-type silicon substrate after the etching damage, in the BBr ₃ gas atmosphere, and by carrying out a thermal diffusion treatment under the conditions of 20 minutes at a temperature of 900 ℃, has already formed the emitter layer of p-type diffusion layer and the glass layer. The sheet resistance of the formed p-type diffusion layer was about 70? / ?, and the diffusion depth was 0.5 占 퐉. This substrate was immersed in a 25% aqueous solution of hydrofluoric acid, then rinsed with pure water and dried to remove the glass layer. The substrate on which the glass layer was removed was thermally oxidized in an oxygen atmosphere at a temperature of 1000 DEG C for 120 minutes to form a silicon oxide film with a thickness of 70 nm on both sides of the substrate. Then, a laser beam of a silicon oxide film formed on the back surface of the substrate was irradiated with a fluence of 2 J / cm ^{2 at a position} where a BSF layer was to be formed. As the laser irradiation equipment, Powerline E25 / SHG manufactured by Loftin Co., Ltd. was used. After the laser irradiation, the substrate was immersed in a solution at 70 DEG C containing 25% potassium hydroxide for 5 minutes to remove the p-type diffusion layer remaining in the place where the BSF layer is to be formed by chemical etching, . According to this method, a silicon oxide film thickness of 0 nm and a step lower than the emitter layer formation portion were formed immediately under the laser irradiation, that is, the BSF layer formation site, and the step was formed. Further, the thickness of the silicon oxide film on the emitter layer continuously thinned from 70 nm to 0 nm from the laser irradiation part to both ends of 30 mu m due to the energy propagated from directly under the laser irradiation part.

&Lt; Comparative Example 2 &

Comparative Example 2 is similar to Example 3 except that the laser was irradiated at a fluence of 0.6 J / cm ² . As a result of the laser irradiation, the thickness of the silicon oxide film on the emitter layer continuously thinned from 70 nm to 0 nm from both ends of the laser irradiation part to 0.5 mu m at both ends by the energy propagated from directly under the laser irradiation part.

<Example 4>

Example 4 is similar to Example 3 except that the laser was irradiated with a fluence of 0.9 J / cm ² . As a result of the laser irradiation, the thickness of the silicon oxide film on the emitter layer continuously thinned from 70 nm to 0 nm from both ends of the laser irradiation portion at 1 mu m from the laser irradiation portion due to energy propagated from directly under the laser irradiation portion.

&Lt; Example 5 &gt;

Embodiment 5 is similar to Embodiment 3 except that the laser is irradiated with fluence of 4 J / cm ² . As a result of the laser irradiation, the thickness of the silicon oxide film on the emitter layer continuously thinned from 70 nm to 0 nm from both ends of the laser irradiation part to both ends by the energy propagated from directly under the laser irradiation part.

&Lt; Comparative Example 3 &

Comparative Example 3 is similar to Example 3 except that the laser was irradiated with a fluence of 5.5 J / cm ² . As a result of the laser irradiation, the thickness of the silicon oxide film on the emitter layer continuously thinned from 70 nm to 0 nm at both ends of 150 mu m from the laser irradiation part by the energy propagated from directly under the laser irradiation part.

&Lt; Example 6 &gt;

Embodiment 6 is similar to Embodiment 2 except that a silicon oxide film is formed without removing the glass layer after forming the emitter layer. Specifically, the following steps were carried out and then the first and second common processes described later were carried out.

The entire back surface of the n-type silicon substrate after the damage etching, BBr ₃ gas in the atmosphere, forming a by carrying out a thermal diffusion process, the p-type diffusion emitter layer on the back surface of the substrate and the glass layer under the conditions of 20 minutes at a temperature of 900 ℃ Respectively. Subsequently, the substrate was not removed from the heating furnace, and only the gas was substituted for the oxygen atmosphere, and the substrate was thermally oxidized at a temperature of 1000 캜 for 120 minutes to form a silicon oxide film on the glass layer. The sheet resistance and the diffusion depth of the formed p-type diffusion layer were about 80? /? And 1.0 占 퐉, respectively, and a glass layer and a silicon oxide film serving as a protective film were formed as a laminate with a total film thickness of 100 nm. Then, an etching paste was screen-printed on a portion of the laminate of the glass layer and the silicon oxide film formed on the back surface of the substrate where the BSF layer was to be formed, and heated at 300 캜 for drying. Here, SolarEtch (registered trademark) BES Type 10 paste manufactured by Merck was used as the etching paste. Then, the substrate was immersed in a solution containing 1% of potassium hydroxide to remove the etching paste. This substrate was immersed in a solution at 70 캜 containing 25% potassium hydroxide for 5 minutes to remove the p-type diffusion layer remaining in the place where the BSF layer was to be formed, by chemical etching, and then washed with pure water and dried. According to this method, the portion where the etching paste was printed, that is, the portion where the BSF layer was formed, had a thickness of 0 nm and a lower step than that of the emitter layer formation. The thickness of the laminated body of the glass layer and the silicon oxide film on the emitter layer continuously thinned from 100 nm to 0 nm at both ends from the etching paste printing portion through the etching paste permeated from the etching paste after printing.

&Lt; First common process &gt;

Thermal diffusion treatment was performed on the back surfaces of the respective substrates obtained through the processes shown in the above Comparative Examples 1 to 3 and Examples 1 to 6 under the conditions of a temperature of 930 캜 for 20 minutes in a POCl ₃ gas atmosphere, Phosphorus was diffused into the removed portion to form an n-type diffusion layer which is a BSF layer and a glass layer. The sheet resistance of the formed n-type diffusion layer was about 30? / ?, and the diffusion depth was 0.5 占 퐉. In each of Embodiments 1 to 6, phosphorus diffuses continuously from the portion where the thickness of the silicon oxide film is reduced to the emitter layer, thereby forming a high-resistance layer in which boron and phosphorus are mixed with each other. The sheet resistance of this high-resistance layer could not be accurately measured, but it was 1000? /? Or more. Thereafter, these substrates were immersed in a 25% aqueous solution of hydrofluoric acid, washed with pure water and dried to remove the silicon oxide film and the glass layer.

&Lt; Example 7 &gt;

Example 7 was fabricated in the same manner as in Example 3 except that the BSF layer and the high-resistance layer were formed after the emitter layer was formed in Example 3, while in Example 7, after the BSF layer was formed, Resistance layer is formed. Specifically, the following steps were carried out and then a second common step, which will be described later, was carried out.

A thermal diffusion process was performed on the entire back surface of the n-type silicon substrate after damage etching under the condition of a temperature of 930 캜 for 20 minutes in a POCl ₃ gas atmosphere to form an n-type diffusion layer and a glass layer as a BSF layer. The sheet resistance of the formed n-type diffusion layer was about 30? / ?, and the diffusion depth was 0.5 占 퐉. Thereafter, this substrate was immersed in a 25% aqueous solution of hydrofluoric acid, washed with pure water and dried to remove the silicon oxide film and the glass layer. The substrate on which the glass layer was removed was thermally oxidized in an oxygen atmosphere at a temperature of 1000 DEG C for 120 minutes to form a silicon oxide film with a thickness of 70 nm on both sides of the substrate. Then, a laser beam of ² J / cm ² was applied to a portion of the silicon oxide film formed on the back surface of the substrate where the emitter layer is to be formed. As the laser irradiation equipment, Powerline E25 / SHG manufactured by Loftin Co., Ltd. was used. After the laser irradiation, the substrate was immersed in a solution at 70 DEG C containing 25% potassium hydroxide for 5 minutes to remove the n-type diffusion layer remaining in the portion where the emitter layer is to be formed by chemical etching, . According to this method, the portion directly under the laser irradiation, that is, the portion where the emitter layer is to be formed, was formed to have a thickness of 0 nm and a lower level than the BSF layer formation portion, and a step was formed. Further, the thickness of the silicon oxide film on the BSF layer continuously thinned from 70 nm to 0 nm from both ends of the laser irradiation part to both ends of 30 mu m due to the energy propagated from directly under the laser irradiation part. Subsequently, thermal diffusion treatment is performed on the back surface of the substrate under the condition of BBr ₃ gas atmosphere at a temperature of 930 ° C for 20 minutes to diffuse boron to the portion from which the silicon oxide film has been removed to form a p-type diffusion layer and a glass layer Respectively. The sheet resistance of the formed p-type diffusion layer was about 80? / ?, and the diffusion depth was 1.0 占 퐉. Boron is also diffused into the BSF layer continuously from the portion where the thickness of the silicon oxide film is thinned, thereby forming a high-resistance layer in which boron and phosphorus are mixed with each other. Thereafter, this substrate was immersed in a 25% aqueous solution of hydrofluoric acid, washed with pure water and dried to remove the silicon oxide film and the glass layer.

&Lt; Second common process &gt;

Resist paste was screen-printed on the entire back surface of each of the substrates on which the emitter layer, the BSF layer, and the high-resistance layer were formed by the processes shown in Comparative Examples 1 to 3 and Examples 1 to 7, . As the resist paste, a 185 paste manufactured by LEKTRACHEM was used. The substrate was chemically etched with a solution of 2% potassium hydroxide and 2% IPA at 70 캜 for 5 minutes, then cleaned with pure water and dried to form a textured structure on the light receiving surface of the substrate. Thereafter, the substrate was immersed in acetone to remove the resist paste.

Next, a silicon nitride film serving as an antireflection film and passivation film was formed to a thickness of 100 nm on the light receiving surface and the back surface of the substrate by the plasma CVD method using SiH ₄ , NH ₃ , and N ₂ .

A conductive silver paste was printed on the emitter layer of the substrate processed as described above by screen printing and dried at 150 ° C. Then, a conductive silver paste was printed on the BSF layer of the substrate by screen printing and dried at 150 ° C. In this case, in the comparative examples 1 and 2, the positions where the electrodes were shifted from the BSF layer to the emitter layer and were vacated were confirmed. On the other hand, in Examples 1 to 7, the positions where the electrodes were displaced and vacated on the high-resistance layer between the BSF layer and the emitter layer were confirmed. As the conductive silver paste, SOL9383M manufactured by Heraeus was used. The printed conductive pastes thus baked were fired at a maximum temperature of 800 DEG C for 5 seconds to produce the back electrode type solar cell of each of Comparative Examples and Examples.

<Conductivity>

The average conversion efficiency, the average short-circuit current density, the average open-circuit voltage, and the average curve factor of the back electrode type solar cell produced by the methods of Comparative Examples 1 to 3 and the methods of Examples 1 to 7, Respectively.

As shown in Table 1, in any of the other examples having the structure of the present invention, a high value was obtained for any characteristic value as compared with Comparative Example 1 using the conventional structure. Comparing the characteristic values of Examples 3 to 5 and Comparative Examples 2 and 3 having different widths of the high-resistance layer to each other, it is found that if the width of the high-resistance layer is narrower than 1 탆 as in Comparative Example 2, The curve factor decreases. On the contrary, if the width is larger than 100 탆 as in Comparative Example 3, the short-circuit current decreases due to the reduction of the area of the emitter layer, and the conversion efficiency deteriorates. Therefore, in order to obtain excellent conversion efficiency expected in the back electrode type solar cell of the present invention, the width of the high resistance layer may be designed to be not less than 1 탆 and not more than 100 탆.

101 semiconductor substrate
102 Shield
103 Resist paste
104 emitter layer
105 glass layer
106 BSF layer
107, 108 Antireflection film and passivation film
109, 110 electrode
201 Etching Paste
202 High resistance layer

Claims (11)

On the back surface which is the non-light-emitting surface of the semiconductor substrate of the first conductivity type,
A first conductivity type diffusion layer in which an impurity of the first conductivity type is diffused,
A second conductivity type diffusion layer in which an impurity of the second conductivity type is diffused,
And a high resistance layer or an intrinsic semiconductor layer formed between the first conductivity type diffusion layer and the second conductivity type diffusion layer. The method according to claim 1,
A first electrode connected to the first conductivity type diffusion layer, and a second electrode connected to the second conductivity type diffusion layer,
Wherein either one of the first electrode and the second electrode is connected to the high-resistance layer or the intrinsic semiconductor layer. 3. The method according to claim 1 or 2,
A step is provided on the back surface,
Wherein one of the first conductivity type diffusion layer and the second conductivity type diffusion layer is provided on the upper end and the other is provided on the lower end,
Wherein the high resistance layer or the intrinsic semiconductor layer is provided on the top. 4. The method according to any one of claims 1 to 3,
The high resistance layer or the intrinsic semiconductor layer is formed to have a width that separates the first conductive type diffusion layer and the second conductive type diffusion layer at intervals of not less than 1 mu m and not more than 100 mu m Photoelectric conversion efficiency solar cell. 5. The method according to any one of claims 1 to 4,
Wherein the high-resistance layer diffuses both the impurity of the first conductivity type and the impurity of the second conductivity type. A second conductivity type diffusion layer in which impurities of the second conductivity type are diffused is formed in the first region on the back surface which is the non-light-receiving surface of the first conductivity type semiconductor substrate having the first region, the second region and the third region Forming a first conductive type diffusion layer in which impurity of the first conductivity type is diffused in the second region, and forming a second conductive type impurity in the third region between the first region and the second region, A method of manufacturing a high photoelectric conversion efficiency solar cell in which a high resistance layer in which impurities of a second conductivity type are diffused is formed,
A second impurity diffusion step of diffusing the impurity of the second conductivity type on the entire surface of the back surface of the semiconductor substrate to form a second conductivity type diffusion layer;
A protective film forming step of forming a protective film on the second conductive type diffusion layer;
The thickness of the portion of the protective film covering the third region is continuously thinned from the boundary of the portion covering the first region to the boundary of the portion covering the second region so as to become substantially zero from the film thickness, A first protective film removing step of removing a portion of the protective film covering the second region,
A second conductive type diffusion layer removing step for removing the exposed second conductive type diffusion layer to expose the second region,
The first conductivity type impurity is diffused into the third region through the continuously thinned portion of the second region and the protective film to form the first impurity diffusion layer and the first impurity diffusion layer, A spreading step,
And a second protective film removing step for removing the remaining protective film. A second conductivity type diffusion layer in which impurities of the second conductivity type are diffused is formed in the first region on the back surface which is the non-light-receiving surface of the first conductivity type semiconductor substrate having the first region, the second region and the third region Forming a first conductivity type diffusion layer in which impurities of the first conductivity type are diffused in the second region, and forming a second conductivity type impurity of the first conductivity type in the third region between the first region and the second region, Forming a high-resistance layer in which an impurity of the second conductivity type is diffused, the method comprising:
A first impurity diffusion step of diffusing the impurity of the first conductivity type on the entire back surface of the semiconductor substrate to form a first conductivity type diffusion layer;
A protective film forming step of forming a protective film on the first conductive type diffusion layer;
The thickness of the portion of the protective film covering the third region is continuously thinned from the boundary of the portion covering the first region to the boundary of the portion covering the second region so as to become substantially zero from the film thickness, A first protective film removing step of removing a portion of the protective film covering the second region,
A first conductive type diffusion layer removing step of removing the exposed first conductive type diffusion layer to expose the second region;
The second conductive type diffusion layer and the second impurity which forms the high resistance layer are formed by diffusing the impurity of the second conductive type into the third region through a continuously thinned portion of the second region and the protective film, A spreading step,
And a second protective film removing step for removing the remaining protective film. 8. The method according to claim 6 or 7,
Wherein the protective film is removed and thinned in the first protective film removing step by application of an etching paste to a portion of the protective film covering the second region or laser irradiation, &Lt; / RTI &gt; 9. The method according to any one of claims 6 to 8,
Wherein the protective film is a silicon oxide film, a silicon nitride film, an impurity-containing glass layer, or a laminate of two or more thereof. A solar cell module comprising a plurality of high photoelectric conversion efficiency solar cells according to any one of claims 1 to 5. A solar power generation system comprising the solar cell module according to claim 10.

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